The present disclosure generally relates to a method and system for providing ventilator therapy to a patient. More specifically, the present disclosure relates to a method of adjusting the operation of a ventilator to compensate for the flow of gas created by an external gas source, such as a nebulizer, to improve the ventilation therapy.
Clinicians commonly utilize a nebulizer to provide aerosoled drug delivery to a patient that is connected to a ventilator. Nebulizers are typically placed in the inspiratory limb of a patient circuit and are used to inject an aerosoled drug directly into the flow stream of the breathing gases for the patient. Nebulizers are typically pneumatic or ultrasonic technology-based devices that are run continuously for a period of time until delivery of discrete doses of the drug or agent have been completed.
When utilizing a pneumatic nebulizer, the nebulized agent supplied to the patient is received from the nebulizer entrained in a nebulizer gas flow. The nebulizer gas flow including the entrained nebulized agent is added to the flow of gas from the ventilator such that the combined gas flow is provided to the patient during the inspiratory phase.
Although the use of a nebulizer to introduce a nebulized agent into the flow of gas to the patient functions well to deliver the nebulized agent, the addition of the nebulizer gas flow to the gas flow from the ventilator can create problems. In most modern ventilators, the flow of gas from the nebulizer is added downstream from the sensors that measure the inspiratory gas flow from the ventilator. In such an embodiment, the gas flow measured during the expiratory phase is higher than the corresponding inspiratory volume from the ventilator. The increased volume of the expiratory gas flow can lead to unnecessary alarm conditions in the ventilator. Without some type of compensation for the flow provided by the nebulizer or other external device, the ventilator can generate unnecessary alarms, which significantly reduces the reliability of the volumes measured during the inspiratory and expiratory phase. Alternatively, the patient could be over-ventilated due to the unmeasured inspiratory flow from the nebulizer.